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چکیده
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Background: Organic trace minerals (TM) offer potential benefits for poultry health and productivity; however, their effectiveness under heat stress (HS) conditions is not well characterized. This study aimed to evaluate the effects of supplementing broiler diets with an advanced chelate-based trace mineral complex (ATMC) under cyclic HS conditions. Methods: A total of 600 one-day-old Ross 308 broilers were randomly assigned to five dietary treatment groups for a 42-day study: (1) TC, which received a basal diet supplemented with the commercial levels of inorganic trace minerals (ITM) under thermoneutral conditions; (2) HSC, which consisted of a basal diet with the com mercial ITM levels under heat stress; (3) ITM+ATMC12.5; (4) ITM+ATMC25, where diets were supplemented with 12.5 % and 25 % additional TM from ATMC, respectively, under HS; and (5) ITM125, which included a diet with 125 % of the recommended ITM levels under HS. Results: The ITM+ATMC25 group exhibited significantly higher weight gain, European Production Efficiency Index, serum T4 concentration, and duodenal villus height compared to the HSC group, with results comparable to the TC group. Additionally, feed conversion ratio, mortality rate, abdominal fat, liver weight, heterophil-tolymphocyte ratio, alkaline phosphatase activity, and corticosterone concentration were lower in the TC and ITM+ATMC25 groups compared to the HSC group. The expression levels of heat shock protein (HSP) 70 in the liver and hypothalamus were lower in the TC and ITM+ATMC25 groups, indicating improved stress resilience. Furthermore, hepatic HSP90 expression was downregulated in the TC, ITM+ATMC12.5, and ITM+ATMC25 groups compared to the HSC group. Conclusion: The results indicate that adding 25 % more TM provided by ATMC than the recommended ITM levels can positively affect growth, intestinal structure, and stress-related physiological responses in broilers exposed to HS.
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